UAV configurations and battery augmentation for UAV internal combustion engines, and associated systems and methods

ABSTRACT

UAV configurations and battery augmentation for UAV internal combustion engines, and associated systems and methods are disclosed. A representative configuration includes a fuselage, first and second wings coupled to and pivotable relative to the fuselage, and a plurality of lift rotors carried by the fuselage. A representative battery augmentation arrangement includes a DC-powered motor, an electronic speed controller, and a genset subsystem coupled to the electronic speed controller. The genset subsystem can include a battery set, an alternator, and a motor-gen controller having a phase control circuit configurable to rectify multiphase AC output from the alternator to produce rectified DC feed to the DC-powered motor. The motor-gen controller is configurable to draw DC power from the battery set to produce the rectified DC feed.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of International Patent ApplicationNo. PCT/US2015/019004, entitled “UAV CONFIGURATIONS AND BATTERYAUGMENTATION FOR UAV INTERNAL COMBUSTION ENGINES, AND ASSOCIATED SYSTEMSAND METHODS,” and filed on Mar. 5, 2015, which claims priority to U.S.Provisional Patent Application No. 61/952,675, entitled “BATTERYAUGMENTATION FOR INTERNAL COMBUSTION ENGINE, AND ASSOCIATED SYSTEMS ANDMETHODS” and filed on Mar. 13, 2014, and U.S. Provisional PatentApplication No. 62/037,021, entitled “BATTERY AUGMENTATION FOR INTERNALCOMBUSTION ENGINE, AND ASSOCIATED SYSTEMS AND METHODS” and filed on Aug.13, 2014, each of which are incorporated by reference herein in theirentirety.

TECHNICAL FIELD

This disclosure relates generally to DC power supplies for drivingmotors, and in particular to a DC power supply for an unmanned aerialvehicle (UAV) with multiple rotors. The DC power supply can be used topower a variety of UAVs, including UAVs with combinations ofvariable-incidence wings and multiple rotors.

BACKGROUND

Conventional power supplies for multi-rotor UAVs are generally directcurrent (DC) batteries. However, most batteries have limited energydensity. Accordingly, a battery-only power source provides limitedendurance and cannot sustain long range travel for the UAV. Otheralternative power sources used by existing multi-rotor vehiclesintroduce additional problems, such as unpredictable fluctuations in thepower supplied to the rotors, thus causing instability in flight.

SUMMARY

Disclosed are DC power supply systems (e.g., a genset subsystem of aUAV) that utilizes high energy density liquid fuel to increase thetravel endurance of multi-rotor vehicles. The disclosed DC power supplysystem includes a lightweight and high powered energy conversionpipeline that drives an electronic powertrain. The energy conversionpipeline is at least partially powered by liquid fuel. In at least oneembodiment, the energy conversion pipeline includes an internalcombustion engine (ICE) and a brushless direct current (BLDC)alternator. Embodiments of the disclosed DC power supply system alsoinclude a battery module having one or more batteries. Embodiments ofthe disclosed DC power supply system provides a stable DC voltage todrive multiple rotors under various operational modes including anEngine Start Mode, a generator only mode, a generator-based ripplemitigation mode, a generator with automated Battery Augmentation Mode, agenerator with Assisted Augmentation Mode, a Battery-Only Mode, or anycombination thereof.

The disclosed DC power supply system can implement a hybrid vehiclepower supply that uses both an internal combustion engine and a set ofbatteries. This implementation is superior to traditional hybrid powersupplies that are “in series”, where an internal combustion enginecharges a battery, and a motor is driven only by the power supplied fromthe battery. This implementation is also superior to traditional hybridpower supplies that operate as “alternatives” of one another, where themotor is driven either by the ICE or the battery.

Some embodiments of the disclosure have other aspects, elements,features, and steps in addition to or in place of what is describedabove. Several of these potential additions and replacements aredescribed throughout the rest of the specification

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram of a representative system architecture of amulti-rotor vehicle, in accordance with at least some embodiments.

FIG. 1B is an illustration of a portion of a representative vehicle onwhich embodiments of the systems disclosed herein can be installed.

FIG. 2 is a block diagram of a representative system architecture of anavionics subsystem of a vehicle, in accordance with at least someembodiments.

FIG. 3 is a block diagram of a representative system architecture of agenset subsystem of a vehicle, in accordance with at least someembodiments.

FIG. 4 is a current flow diagram within the genset subsystem of FIG. 3in a Ground-Level Engine Start Mode, in accordance with at least someembodiments.

FIG. 5 is a current flow diagram within the genset subsystem of FIG. 3in an Inflight Engine Start Mode, in accordance with at least someembodiments.

FIG. 6 is a current flow diagram within the genset subsystem of FIG. 3in a Generator-Only Mode, in accordance with at least some embodiments.

FIG. 7 is a current flow diagram within the genset subsystem of FIG. 3in a Ripple Mitigation Mode or a Battery Augmentation Mode, inaccordance with at least some embodiments.

FIG. 8 is a current flow diagram within the genset subsystem of FIG. 3in a Battery-Only Mode, in accordance with at least some embodiments.

FIG. 9 is a current flow diagram within the genset subsystem of FIG. 3in a Battery Charging Sub Mode, in accordance with at least someembodiments.

FIG. 10 is a block diagram of a representative system architecture of amotor-gen controller in a genset subsystem of a vehicle, in accordancewith at least some embodiments.

FIG. 11 is a first exemplary circuit diagram of phase controllers withina motor-gen controller in a genset subsystem of a vehicle, in accordancewith at least some embodiments.

FIG. 12 is second exemplary circuit diagram of phase controllers withina motor-gen controller in a genset subsystem of a vehicle, in accordancewith at least some embodiments.

FIG. 13 is a first exemplary circuit diagram of an augmentationcontroller within a motor-gen controller in a genset subsystem of avehicle, in accordance with at least some embodiments.

FIG. 14 is second exemplary circuit diagram of an augmentationcontroller within a motor-gen controller in a genset subsystem of avehicle, in accordance with at least some embodiments.

FIG. 15 is a partially schematic plan-view illustration of a vehiclehaving lift rotors and axial thrust rotors in combination with a powergeneration system configured in accordance with an embodiment of thepresent technology.

FIG. 16 is a partially schematic, plan-view illustration of a vehiclehaving multiple lift rotors, a tractor rotor, and dynamically modifiablewing geometries in accordance with an embodiment of the presenttechnology.

FIG. 17 is a partially schematic, plan-view illustration of an airvehicle having a configuration generally similar to that described abovewith reference to FIG. 16, without a tractor rotor.

FIG. 18 is a partially schematic plan-view illustration of an airvehicle having dynamically modifiable wings and lift rotor pods inaccordance with another embodiment of the present technology.

FIG. 19 is a partially schematic, plan-view illustration of an airvehicle having dynamically modifiable lift rotor pods in combinationwith a power generation system in accordance with an embodiment of thepresent technology.

FIG. 20 is a partially schematic, side view of an air vehicle having afixed wing and a movable rotor boom in accordance with yet anotherembodiment of the present technology.

FIG. 21 is a partially schematic, top isometric view of an air vehiclehaving lift rotor pods that are controllable in accordance with anotherembodiment of the present technology.

FIG. 22 is a third exemplary circuit diagram of phase controllers withina motor-gen controller in a gen-set subsystem of a vehicle, inaccordance with at least some embodiments.

FIG. 23 is a block diagram illustrating a health monitor system inaccordance with at least some embodiments.

The figures depict various embodiments for purposes of illustrationonly. One skilled in the art will readily recognize from the followingdiscussion that alternative embodiments of the structures and methodsillustrated herein may be employed without departing from the principlesof the disclosure described herein.

DETAILED DESCRIPTION

The present technology is directed generally to unmanned aerial vehicle(UAV) configurations and battery augmentation for UAV internalcombustion engines. Several details describing structures and processesthat are well-known and often associated with these types of systems andprocesses, but that may unnecessarily obscure some significant aspectsof the presently disclosed technology, are not set forth in thefollowing description for purposes of clarity. Furthermore, although thefollowing disclosure sets forth several embodiments of different aspectsof the disclosed technology, several other embodiments can havedifferent configurations and/or different components than thosedescribed in this section. Accordingly, the disclosed technology mayinclude other embodiments with additional elements not described belowwith reference to FIGS. 1A-23 and/or without several of the elementsdescribed below with reference to FIGS. 1A-23.

Several embodiments of the technology described below may take the formof computer-executable instructions, including routines executed by aprogrammable computer and/or controller. For example, embodimentsrelating to methods of powering, controlling, flying and/or otherwiseoperating a UAV can be implemented via computer-executable instructions.Persons having ordinary skill in the relevant art will appreciate thatthe technology can be practiced on computer and/or controller systemsother than those described below. The disclosed technology can beembodied in a special-purpose computer, controller or data processorthat is specifically programmed, configured or constructed to performone or more of the computer-executable instructions. Accordingly, theterms “computer” and “controller” as generally used herein refer to anysuitable data processor and can include Internet appliances andhand-held devices (including palm-top computers, wearable computers,cellular or mobile phones, multi-processor systems, processor-based orprogrammable consumer electronics, network computers, mini computers andthe like). Information handled by these computers can be presented atany suitable display medium.

The technology can also be practiced in distributed environments, wheretasks or modules are performed by remote processing devices that arelinked through a communications network. For example, a controller in asystem in accordance with the present disclosure can be linked with andcontrol other components in the system. In a distributed computingenvironment, program modules or subroutines may be located in local andremote memory storage devices. Aspects of the technology described belowmay be stored or distributed on computer-readable media, includingmagnetic or optically readable or removable computer disks, as well asdistributed electronically over networks.

1.0 Overview

The present disclosure describes both UAV configurations and powersystems to provide battery augmentation for internal combustion enginesused by UAVs. In some embodiments, the disclosed UAV configurationsinclude the battery augmentation systems, and in other embodiments, thedisclosed UAV configurations need not include the disclosed batteryaugmentation systems. Similarly, the disclosed battery augmentationsystems can be implemented on UAV configurations other than those shownand described below. In general, the battery augmentation aspects of thedisclosure are described below under headings 2.0-8.0, and further UAVconfigurations are described under heading 9.0.

2.0 Multi-Rotor Vehicle System

FIG. 1A is a block diagram of a representative system architecture of amulti-rotor vehicle 100, in accordance with at least some embodiments. Arepresentative vehicle platform is shown in FIG. 1B. The multi-rotorvehicle, for example, can be a rotary wing vehicle utilizing eightelectrically driven fixed pitch rotors. As used herein, the term “rotor”is used to include rotors, propellers and any other suitable rotatingblade or blade-type structure that imparts a force to a vehicle viainteraction with the surrounding fluid medium. The multi-rotor vehiclecan include multiple subsystems. The subsystems can include an avionicssubsystem 102, a genset subsystem 104, one or more of electronic speedcontrollers (ESCs) 106 (e.g., 8 controllers in a vehicle with 8 rotors),and one or more drive motors 108 that drive one or more rotors 110(e.g., propellers). In some embodiments, a drive motor is “coupleable”to a rotor/propeller. That is, the drive motor is adapted in a structurethat is capable of being coupled to the rotor/propeller.

The multi-rotor vehicle 100 can contain one or more avionics batteries112 and one or more vehicle batteries 114. One or more (e.g., all) drivemotors 108 and rotors 110 combinations can be powered by three phasealternating current (AC) electrical power, supplied by one of thededicated electronic speed controllers (ESC) 106.

The ESCs 106 can be powered by a common direct current power bus(hereinafter, the “DC motor bus 116”). The DC motor bus 116 is poweredby the genset subsystem 104, whose primary role is to convert liquidfuel into DC power via a microcontroller-managed motor-generatorconversion pipeline. The genset subsystem 104 can include amicrocontroller to manage the motor-generator conversion pipeline. Thethrust produced by each of the ESCs 106, the drive motors 108, and therotors 110 combination can be controlled via dedicated, unidirectionalserial links that use pulse width modulation (PWM) encoded controlsignals, connected to the avionics subsystem 102.

FIG. 1B is an illustration of a portion of a representative vehicle,such as the multi-rotor vehicle 100, on which embodiments of the systemsdisclosed herein can be installed.

FIG. 2 is a block diagram of a representative system architecture for anavionics subsystem 200 of a vehicle (e.g., the multi-rotor vehicle 100of FIG. 1), in accordance with at least some embodiments. For example,the avionics subsystem 200 can be, or be part of, the avionics subsystem102 of FIG. 1A.

The avionics subsystem 200 can facilitate remotely piloted flightcontrol and/or autonomous flight control. The avionics subsystem 200 caninclude at least the following functional blocks: a flight controller202, an autopilot module 204, a DC-DC Converter 206, a micro air vehiclelink (MAVLink) Interface 208, a telemetry transceiver 210, an auxiliaryremote control receiver 212, a global positioning system (GPS) receiver214, a magnetometer 216, a barometric pressure sensor 218, or anycombination thereof.

Most multi-rotor vehicles are neither dynamically nor statically stable,and thus require active flight stabilization. The flight controller (FC)202 can be a module contained within the operating code of an avionicscontroller 220 (e.g., an avionics microcontroller). The avionicscontroller 220 can be connected to the vehicle ESCs, thus controllingthe thrust produced by each drive motor/rotor combination and providingstabilized flight.

The flight controller 202 can use a six-axis accelerometer array 222 toascertain the specific thrust levels that each motor/prop combinationneeds to produce, in order to maintain, or change, desired accelerationvalues over three rotational axes and three translational planes. Theflight controller 202 is also capable of holding a preset vehicleorientation (i.e., maintaining zero velocity across all three axis). Theflight controller 202 can either be commanded by a ground based pilot(under a Fully Manual Remotely Piloted Operation Mode), an autopilot(under an Autonomous Operation Mode), or a combination of manualcommands from a ground based pilot and an autopilot-based augmentation(under a Fly-By-Wire Operation Mode). The flight controller 202 receivescontrol information from any individual or combination of commandsources depending on which mode is active and/or whether the avionicssubsystem 200 is using primary or backup radio frequency (RF) controllinks. The command sources can include: the telemetry transceiver 210(e.g., interfaced through the MAVLink interface 208 via interprocesscommunication (IPC)); the auxiliary remote control receiver 212 (e.g.,PWM links); and an Inter-Process Communication (IPC) link from theautopilot module 204.

The autopilot module 204 can be contained within the operating code ofthe avionics controller 220. The autopilot module 204 provides at leasttwo functions, including execution of stored flight plans during theautonomous flight operation mode and integration of GPS, barometricaltimetry, and magnetometer data during the Fly-by-Wire modes operationmode.

The autopilot module 204 can be connected to both the GPS receiver 214(e.g., via a TTL Serial Link) and the magnetometer 216 (e.g., via an I2Clink). The autopilot module 204 can be connected to the barometricpressure sensor 218 via its IPC link. External to the vehicle, theautopilot module 204 can also connect with a control station via theMAVLink interface 208 (e.g., IPC-connected interface) and the telemetrylink. The autopilot module 204 can further be connected to a dedicatedremote handheld flight controller via PWM links through the auxiliaryremote control receiver 212 (e.g., a radio receiver).

All avionics functions in the avionics subsystem 200 can be powered bythe DC-DC converter 206 (e.g., a dedicated DC-DC converter). The DC-DCconverter 206 is powered by one or more avionics batteries in thevehicle. Alternatively, the DC-DC converter 206 can also be powered by agenset subsystem, such as the genset subsystem 104 of FIG. 1A or thegenset subsystem 300 of FIG. 3. The DC-DC converter can also receivebackup power or power augmentation from the genset subsystem.

FIG. 3 is a block diagram of a representative system architecture of agenset subsystem 300 of a vehicle (e.g., the multi-rotor vehicle 100 ofFIG. 1), in accordance with at least some embodiments. For example, thegenset subsystem 300 can be the genset subsystem 104 of FIG. 1. Thegenset subsystem 300 implements the disclosed DC power supply systemthat enables battery power to augment power generated from an internalcombustion engine (ICE) 302. In some embodiments, another fuel-basedpower source can replace the ICE 302. For example, a fuel-based powersource can generate mechanical movement and couple the mechanicalmovement input to an alternator 306.

The genset subsystem 300 implements an energy conversion pipeline thatconverts liquid fuel to electrical energy through the ICE 302 and thealternator 306, such as a brushless DC alternator. The alternator 306can have a mechanical movement input and a multiphase alternatingcurrent output. The energy conversion pipeline can have a high ratio ofconversion pipeline weight to power density. This ratio is referred toas the pipeline conversion efficiency (PCE). The genset subsystem 300can advantageously use lightweight hardware controlled by a complexpower management system implemented by a microcontroller 308. Themicrocontroller 308 receives monitor sensor links to determine the stateof the genset subsystem 300 and outputs various control links to adjustvarious components of the genset subsystem 300. FIG. 3 illustratesexamples of the sensor links and the control links as shaded boxes. Thiscombination enables the use of the ICE 302 by implementing a way tostabilize the DC power output of the ICE 302. The genset subsystem 300is able to reach higher levels of PCE that are normally unreachable byconventional power management systems.

The disclosed vehicle uses the ICE 302 (e.g., a lightweight ICE) tomechanically drive the alternator 306. For example, the alternator 306can be a multi-phase alternator (e.g., The alternator 306 through atransmission. In at least some cases, neither the ICE 302, nor thealternator 306 are necessarily well suited for powering electricallydriven multi-rotor vehicles due to the ripples in the power theygenerate. The ICE 302 and the alternator 306 are, however, among thehighest density (e.g., watt per lbs) components for converting liquidfuel to raw electrical energy.

In order to gain the benefit of these components (e.g., the very highconversion density), the disclosed vehicle implements control modulesvia the microcontroller 308 to carefully monitor and actively controlboth the ICE 302 and other components within the conversion pipeline.

The energy conversion pipeline can begin with fueling the ICE 302. Themicrocontroller 308 can implement a DC motor bus regulation (MBR) module310 that controls the power output and rotational frequency (revolutionsper minute (RPM)) of the ICE 302. The DC MBR module 310 can be a moduleimplemented by the microcontroller 308 executing digital instructionsstored on a persistent digital memory within or outside themicrocontroller 308. The DC MBR module 310 controls the ignition,throttle and fuel/air mixture of the ICE 302. The DC MBR module 310 alsomonitors the current and voltages on both a DC motor bus 312 and thevehicle's battery bus 314, such as when starting up the ICE 302.

A transmission 316 can mechanically connect the ICE 302 and thealternator 306. The alternator 306 can be a multi-phase alternatorhaving three external phase outputs that nominally create a three phaseAC. Each external phase connection can be connected to multiple internalphases within the alternator 306.

This multi-phase configuration of the alternator 306 can maximize themechanical conversion efficiency of the alternator 306 (e.g., in termsof watts per unit torque). This configuration of the alternator 306,however, can produce AC electrical power that contains a highly complexset of waveforms, along with transient inductances.

To address these potential inefficiencies, the genset subsystem 300converts the AC power feed into a direct current (DC) power feed in theDC motor bus 312 by actively rectifying the AC signal and reducinginductance-related power conditioning deficiencies via a motor-gencontroller (MGC) 318. The MGC 318 can also compensate for ripples in theconverted direct-current power feed.

The genset subsystem 300 can also operate by using the alternator 306 asa starter motor for the ICE 302. In order to facilitate this mode ofoperation, the three AC phases of the alternator 306 are connected tothe MGC 318. The MGC 318 can be actively controlled by themicrocontroller 308. The MGC 318 can provide lossless rectification ofthe complex AC power feed into a DC power feed on the DC motor bus 312.The MGC 318 can also provide active and dynamic cancelation ofsynchronous reactance (e.g., Power Factor correction) and provide threephase power to the alternator 306 in order to drive the alternator 306as a motor during a start sequence of the ICE 302. The MGC 318 canfurther enable dynamic integration of the vehicle's battery power bothduring periods of transient power deficits and during a complete failureof the ICE 302 or the alternator 306 (e.g., the vehicle can operate in aBattery-Only Mode, which can be commanded by ground-based operators ifsuch operation is desired). The MGC 318 can yet further provide activemitigation of ripple in the DC output of the genset subsystem 300.

Typical passive rectifiers use a diode that imposes a forward voltagedrop during rectification. This property of a passive rectifier “clips”the peak of an AC input voltage by exactly the amount of the forwardvoltage drop. As an example, if a single phase AC signal with apeak-to-peak voltage of 20V is introduced into a bridge rectifier (e.g.,4 diodes configured to invert the “negative” side of the AC signal), theresulting peak of the DC output would be 10V minus the voltage dropacross the diodes used in the rectifier. For example, for a typicalpower diode, the forward voltage drop is 1.7V, or a 17% drop in the peakvoltage in the above example. Power generally scales as the square ofvoltage. Hence, for example, reducing the voltage to 83% (i.e., 17%drop) reduces the power to around 69% (i.e., 0.83²), resulting in anapproximately 31% power loss. This effect is particularly significant inlow voltage AC applications (e.g., AC power generated from thealternator 306).

In embodiments where the alternator 306 generates lower voltage AC,implementation of passive rectifiers in the MGC 318 would cost areduction in power and would create potential cooling problems in thepassive rectifiers (i.e., from power dissipation associated with thevoltage drop across the diodes). In these embodiments, the MGC 318implements phase controllers to perform active rectification. In severalembodiments, with active rectification, instead of using power diodes,transistors are used as diodes in each of the phase controllers tominimize forward voltage drop (e.g., see FIGS. 11 and 12). For example,the transistors can be field effect transistors (FETs) or bipolartransistors. As a specific example, the FETs can be metal oxidesemiconductor field effect transistors (MOSFETs). As another specificexample, the bipolar transistors can be insulated gate bipolartransistors (IGBTs) Each transistor can include a “body diode.” The MGC318 can reduce resistance and the forward voltage drop across the bodydiode by turning the transistor on (e.g., by applying a suitable gatevoltage to the transistor). The transistors of the phase controllersenable the MGC 318 to emulate a diode-based rectifier without the powerreduction. In some embodiments, diodes are still used as part of thephase controllers (e.g., see FIG. 22).

This reduction of resistance is enabled by use of the N channel in eachFET to cancel the forward voltage drop of the FET's body diode (e.g.,1.7V drop). The MGC 318 turns on a respective FET's N channel (e.g., byapplying suitable gate voltage to the FET) any time the body diode ofthe FET is conducting. The MGC 318 can detect whether the body diode isconducting in at least two ways. The MGC 318 can include a current shuntin each phase controller to sense current flow across the body diode andlocally (e.g., within the phase controller). If the current flowindicates the body diode is conducting, a suitable gate voltage isapplied to the respective FET to turn the FET into saturation. In otherembodiments, the AC phase outputs of the alternator 306 are monitored bythe microcontroller 308. The microcontroller 308 can drive the gatevoltage of respective FETs into saturation based at least partly on themonitored voltage from the alternator 306 (e.g., by determining whetherthe monitored voltage relative to the DC motor bus 312 would cause thebody diode to conduct).

Because a saturated FET can conduct current at very low power loss, therectification process described above can be considered a “losslessrectification.” This feature is advantageous because the FETs can behavelike a diode with an almost immeasurably low forward voltage drop, thusavoiding power loss through the forward voltage drop.

The genset subsystem 300 can operate in different operational modes. Forexample, these operational modes can include an Engine Start Mode, aGenerator-Only Mode, a generator with Ripple Mitigation Mode, agenerator with Battery Augmentation Mode, and a Battery-Only Mode. Atany time the alternator 306 is producing power, a battery charging submode may be activated. The battery charging sub mode can be operationaltogether with the Generator-Only Mode, the generator with RippleMitigation Mode, and the generator with Battery Augmentation Mode.

Any time the alternator 306 is producing power (e.g., the Generator-OnlyMode, the generator with Ripple Mitigation Mode and the generator withBattery Augmentation Mode), the MGC 318 can provide rectification of theAC power feed from the alternator 306. The MGC 318 can operate under tworectification modes as well, including an autonomous rectification modeand an assisted rectification mode.

The genset subsystem 300 can further include a motor bus monitor 320, abattery charger 322, a fuel tank 324, a battery monitor 326, and abattery bus switch 328. The motor bus monitor 320 monitors the voltageand current flow through the DC motor bus 312 for the microcontroller308. The battery charger 322 charges and monitors the vehicle batteries114. The fuel tank 324 stores fuel for the ICE 302. The battery monitor326 monitors the voltage and current through the battery bus 314 for themicrocontroller 308. The battery bus switch 328 connects zero or more ofthe vehicle batteries 114 to the battery bus 314 (zero meaningdisconnecting the battery bus 314 from any battery).

FIG. 4 is a diagram of current flow within the genset subsystem 300 ofFIG. 3 in a Ground-Level Engine Start Mode, in accordance with at leastsome embodiments. In this mode, the microcontroller 308 initiallymonitors the battery bus 314 (labeled as “VBATTERY”) and a fuel level(labeled as “LEVELFUEL”) to ensure both are adequate for the ICE 302 tostart.

The microcontroller 308 then commands 3 phase power (commutated DC) tobe directed toward the alternator 306 via a combination of controlsignals (e.g., control voltage low signal and control voltage highsignal, labeled as “CTRLVL”, “CTRLVH”, respectively) to the MGC 318. Inresponse, the MGC 318 generates the 3 phase commutated DC power. Themicrocontroller 308 also controls the engine throttle of the ICE 302 andthe fuel mixture of the ICE 302 via control signals (e.g., pulse widthmodulated signals) to the ICE 302 (labeled as “PWMTHROTTLE” and“PWMMIXTURE” respectively).

Sensor signals can be fed back to the microcontroller 308. For example,engine rotational speed (e.g., RPM, labeled as “RPMENGINE”), exhaust gastemperature (labeled as “TEMPEGT”), cylinder head temperature (labeledas “TEMPCHT”), and battery bus current (to label as “CBATTERY”) can bemonitored by the microcontroller 308. The battery charge can be used asa proxy for startup torque of the ICE 302. The sensor signals can closethe feedback loop for the ICE 302 startup sequence.

The ICE 302 can be started while the vehicle is on the ground, as wellas while the vehicle is in flight. FIG. 4 depicts a current flow stateof the genset subsystem 300 when starting the ICE 302 on the ground. Oneor more of the vehicle batteries (e.g., the vehicle batteries 114) canbe utilized in this mode. FIG. 5 is a diagram of current flow within thegenset subsystem 300 of FIG. 3 in an Inflight Engine Start Mode, inaccordance with at least some embodiments. In this mode, the DC motorbus 312 is energized by the MGC 318 (e.g., an augmentation controller ofthe MGC 318). The DC motor bus 312 delivers power and thus enables thevehicle's drive motors (e.g., the drive motors 108) to propel thevehicle. The MGC 318 at the same time can commutate power to thealternator 306 so that the alternator 306 can start the ICE 302. Forexample, phase controllers that are used for rectifying AC power fromthe alternator 306 in other modes can now be used to communicate powerto the alternator 306.

3.0 Genset System Operational Modes

3.1 Generator-Only Mode

FIG. 6 is a diagram of current flow within the genset subsystem 300 ofFIG. 3 in a Generator-Only Mode, in accordance with at least someembodiments. In the Generator-Only Mode, all motive power for thevehicle is supplied by the alternator 306. In this mode, themicrocontroller 308 can actively manage both ICE 302's torqueproduction, as well as the various power conditioning functions of theMGC 318.

The microcontroller 308 monitors voltage at the DC motor bus 312 (via asensor link labeled “VMOTOR”). The microcontroller 308 can also manageICE 302's torque output (via a controller link labeled “PWMTHROTTLE”).The microcontroller 308 also manages the efficiency of the ICE 302 byoptimizing mixture by monitoring the exhaust gas temperature (via thesensor link labeled “TEMPEGT”) as a combustion efficiency feedback loop.Rectification of the AC power provided through the alternator 306 isprovided by the MGC 318, either via autonomous or assisted modes.

FIG. 7 is a current flow diagram within the genset subsystem 300 of FIG.3 in a Ripple Mitigation Mode or a Battery Augmentation Mode, in atleast some embodiments.

3.2 Generator with Ripple Mitigation Mode

Operation in the Ripple Mitigation Mode can be identical to theGenerator-Only Mode, with the exception that the one or more of thevehicles' batteries are used by the MGC 318 to remove ripple from therectified output power, prior to output to the DC motor bus 312. In someembodiments, the augmentation controller is configurable to prevent thedirect current from the DC motor bus 312 from flowing into the batterybus 314, and to allow current to flow from the battery bus 314 to the DCmotor bus 312 when a first voltage of the DC motor bus 312 falls below asecond voltage of the battery bus 314.

One feature of this operating mode is the combination of theaugmentation controller's functionality within the MGC 318, and themicrocontroller 308's regulation of the output of the alternator 306. Inthe Ripple Mitigation Mode, the microcontroller 308 monitors the nominalvoltage on the battery bus 314 and utilizes that to control the throttleof the ICE 302. Via the throttle control of the ICE 302, themicrocontroller 308 can ensure that the peak voltage of the DC ripplefrom the rectification process (e.g., via phase controllers in the MGC318) matches the nominal bus voltage of the battery bus 314. Forexample, the augmentation controller is configurable to provide that thealternator produces less voltage than a nominal voltage of a battery inthe battery set.

As a result, during transient troughs in DC ripple in the output of therectification process, the augmentation controller connects the batterybus 314 to the DC motor bus 312. This connection effectively “fills in”the troughs in the DC output with power from the battery bus 314, andcreates a substantially ripple-free output from the MGC 318 to the DCmotor bus 312.

A control link labeled “SELECTBAT” allows the microcontroller 308 toselect which of the vehicle batteries should be used in this mode. Themicrocontroller 308 can select one or more of the vehicle batteries. Forexample, the microcontroller 308 can use one battery for ripplemitigation and charge another battery with the DC power from the DCmotor bus 312.

3.3 Generator with Battery Augmentation Mode

Operation in this mode can be identical to the Generator-Only Mode, withthe exception that the one or more of the vehicle batteries 114 are usedby the MGC 318 to augment the power supplied by the alternator 306.There are two augmentation sub modes when operating under this modeincluding an automated augmentation and a selected augmentation.

3.3A Automated Augmentation Sub Mode

This sub mode is used when the vehicle requires more power than thealternator 306 can provide. This sub mode can either be triggered by acatastrophic failure of some component in the ICE 302, the transmission316, or the alternator 306, or a momentary power deficit due tounusual/extreme flight conditions. This sub mode can also be commandedfrom the microcontroller 308. In some embodiments, when in this submode, the ICE 302's throttle is at a maximum, and the augmentationcontroller mediates transfer of power from the battery bus 314 to the DCmotor bus 312, thus augmenting the power output of the alternator 306with battery power.

The augmentation controller can accomplish this mediation by utilizingthe voltage differential between the DC motor bus 312 and the batterybus 314 to regulate augmentation from the battery, such that as much ofthe power from the alternator 306 as possible is used by the vehicle'sdrive motors (e.g., the drive motors 108), and thus the ship's batteryusage is limited only to that which is needed beyond the maximum powerprovided by the alternator 306.

In particular embodiments, whenever the voltage on the DC motor bus 312(e.g., the root mean square (RMS) voltage produced by the alternator 306and the rectification process) falls below that of the battery bus 314,the augmentation controller directs power from the battery bus 314 tothe DC motor bus 312. Conversely, as the system load decreases such thatthe RMS voltage produced by the alternator 306 and rectification processrises above that of the battery bus 314, the augmentation controllerceases augmenting power on the DC motor bus 312.

3.3B Selected Augmentation Sub Mode

This sub mode allows the microcontroller 308 to command one or more ofthe vehicle batteries 114 to contribute a set amount of current to theDC motor bus 312. This sub mode can be used to reduce the power load onthe ICE 302 when one or more of the ICE 302's thermal limits have beenreached (e.g., the exhaust gas temperature limit or the cylinder headtemperature limit).

This sub mode combines the augmentation controller's functionality andthe microcontroller 308's regulation of voltage output from thealternator 306 into the rectification process. When operating in thissub mode, the microcontroller 308 manages the throttle control of theICE 302, e.g., ensuring the measured current from the battery bus 314(via a sensor link labeled “CBATTERY”) remains at a set currentcontribution level.

If “CBATTERY” falls below the selected set point, the ICE 302's throttleis reduced, thus reducing the torque to the alternator 306. In turn, theRMS voltage of the output from the rectification process to theaugmentation controller is also reduced. This reduction increases thevoltage imbalance between the DC motor bus 312 and battery bus 314,eventually causing the voltage at the DC motor bus 312 to fall relativeto the voltage at the battery bus 314. The falling of the voltage at theDC motor bus 312 causes an increase to the current contribution from thebattery bus 314 through the augmentation controller to the DC motor bus312.

Conversely, if “CBATTERY” rises above the selected set point, the ICE302's throttle is increased, thus increasing the RMS voltage of theoutput from the rectification process in the MGC 318 to the augmentationcontroller. This increases the voltage imbalance between the DC motorbus 312 and the battery bus 314, causing the DC motor bus 312 to riserelative to the battery bus 314. This rise thus decreases the currentcontribution from the battery bus 314 through the augmentationcontroller to the DC motor bus 312.

3.4 Battery-Only Sub-Mode

FIG. 8 is a diagram of the current flow within the genset subsystem ofFIG. 3 in a Battery-Only Mode, in accordance with at least someembodiments. This mode can be considered a special case of the AutomatedAugmentation sub mode described above, used when no power is availablefrom the alternator 306. This mode can either be triggered by a failureof a component in the ICE 302, the transmission 316, or the alternator306, or via command from the microcontroller 308.

As with the Automated Augmentation sub mode, when in the Battery-OnlyMode, the augmentation controller connects the battery bus 314 to the DCmotor bus 312. This ensures that the battery bus 314 provides all thepower required by the DC motor bus 312 to drive the drive motors (e.g.,the drive motors 108).

3.5 Battery-Charging Sub-Mode

FIG. 9 is a diagram of the current flow within the genset subsystem ofFIG. 3 in a battery charging sub mode, in accordance with at least someembodiments. In a particular embodiment, any time the alternator 306 isproducing power, one or more of the vehicle batteries 114 can becharged. When all of the vehicle batteries 114 are being charged, noneof the battery-augmented modes are available (e.g., the RippleMitigation Mode or the Battery Augmentation Mode).

If only a subset of the vehicle batteries 114 are being charged, thenone or more other batteries can be used to enable any of thebattery-augmented modes, and thus ensuring adequate battery chargelevels can be maintained. This enables battery charging to occur evenduring periods when ripple suppression or battery augmentation arenecessary or beneficial. FIG. 9 depicts only one of many batterycharging mode permutations available with the genset subsystem 300. Inthis example, a first battery is being used for one of thebattery-augmented modes, and a second battery is being charged.

FIG. 10 is a block diagram of a representative system architecture of amotor-gen controller (MGC) 1000 in a genset subsystem of a vehicle, inat least some embodiments. For example, the motor-gen controller 1000can be the MGC 318 in the genset subsystem 300.

The MGC 1000 provides a direct linkage within the genset subsystembetween alternator phases 1002 of an alternator (e.g., the alternator306 of FIG. 3) and either or both a DC motor bus 1014 (labeled as“V_(MOTOR)”) and the vehicle's battery bus 1012 (labeled as“V_(BATTERY)”). The alternator phases 1002 can act as either input oroutput from the alternator, depending on the operation mode of thegenset subsystem.

The MGC 1000 includes at least a phase detector 1004 coupled to one ofthe alternator phases 1002. The phase detector 1004 can transmit asensor link labeled “PHASE_(DETECT)” back to a microcontroller of thegenset subsystem (e.g., the microcontroller 308 of FIG. 3). The sensorlink can report the progression of the AC phases to or from thealternator. For example, because the phase difference between thealternator phases 1002 is constant, determining the AC phase of one ofthe alternator phases 1002 enables the microcontroller to determineothers of the alternator phases 1002 at any given time. The phasedetector 1004 provides the microcontroller with an angular referencepoint for the alternator's rotor.

The MGC 1000 also has several phase controllers coupled to thealternator phases 1002, such as two phase controllers per phase. For athree phase alternator, the MGC 1000 can include six phase controllers,including high-side phase controllers (e.g., phase controllers 1006 a,1006 b, and 1006 c, collectively referred to as “high-side phasecontrollers 1006”) and low-side phase controllers (e.g., phasecontrollers 1008 a, 1008 b, and 1008 c, collectively referred to as“low-side phase controllers 1008”).

The DC motor bus 1014 and the battery bus 1012 can each have a highervoltage line and a lower voltage line. Each of the high-side phasecontrollers 1006 can be coupled to the higher voltage line of the DCmotor bus 1014 and the low-side phase controllers 1008 can be coupled tothe lower voltage line of the DC motor bus 1014. An augmentationcontroller 1010 can be coupled to the battery bus 1012 on one side andthe DC motor bus 1014 on the other, enabling some DC current to flowfrom the battery bus 1012 to the DC motor bus 1014 in some operationalmodes of the MGC 1000 and/or the genset subsystem.

In the illustrated example, there are a total of six phase controllersin the MGC 1000. Each alternator phase (e.g., labeled as “U”, “V”, and“W”) is wired into a pair of phase controllers. Each of these alternatorphases 1002 has a phase controller (e.g., one of the high-side phasecontrollers 1006) connected to the positive side of the DC motor bus1014, and a phase controller (e.g., one of the low-side phasecontrollers 1008) connected to the ground of the DC motor bus 1014.

In a particular embodiment, any time the alternator 306 is producingpower, the genset subsystem 300 provides rectification of that power,thus providing DC power to the vehicle. All six of the phase controllers1006 and 1008 can operate together in at least one of three modes:Engine Start Mode, Autonomous Rectification Mode, and AssistedRectification Mode. The microcontroller of the genset subsystem caninstruct the phase controllers in specific operational modes via controllinks (e.g., labeled as “MODE_(R)” in FIG. 10).

3.6 Engine Start Mode

In the Engine Start Mode, each of the phase controllers 1006 and 1008acts as a high speed and low impedance switch, enabling current flowfrom its respective side of the DC motor bus 1014 to its respectivealternator phase. Switching is controlled by the microcontroller of thegenset subsystem, via individual control lines 1016 (e.g., one for eachof the phase controllers 1006 and 1008, labeled as “CTRL_(UH)”,“CTRL_(UL)”, “CTRL_(VH)”, “CTRL_(VL)”, “CTRL_(WH)”, and “CTRL_(WL)”).

The control lines allow the microcontroller of the genset subsystem toconnect either ground or positive to any of the alternator phases 1002.Through this, the phase controllers 1006 and 1008 provide commutatedpower to the alternator during the Engine Start Mode.

4.0 Phase Controller Rectification Modes

4.1 Autonomous Rectification

The Autonomous Rectification Mode of the phase controllers 1006 and 1008enables rectification of AC power from the alternator (e.g., thealternator 306) without external control processes. In this mode, eachof the phase controllers 1006 and 1008 behave like a diode with a verylow (e.g., below 1 mV) forward voltage drop. As a result, the six phasecontrollers 1006 and 1008 can behave similar or identical to a 3 phasebridge rectifier, except without any meaningful voltage drop.

Like diodes, the high-side phase controllers 1006 connect to respectivealternator phases 1002 to the positive side of the DC motor bus 1014when the high-side phase controllers 1006 sense a positive slope zerocrossing on their respective alternator phases 1002. In similar fashion,the low-side phase controllers 1008 connect to respective alternatorphases 1002 to the ground side of the DC motor bus 1014 when thelow-side phase controllers 1008 sense a negative slope zero crossing ontheir respective alternator phases 1002.

4.2 Assisted Rectification

This rectification mode is used when the alternator characteristics andthe system load create synchronous reactance (e.g., phase differencesbetween the voltage and current consumed by the electronic speedcontrollers of the vehicle, such as the ESCs 106 of FIG. 1) that exceedsthe electronic speed controllers' capacity for compensation. That is,the microcontroller instructs the phases controllers 1006 and 1008 toperform assisted rectification when the power factor of the combinedload falls too far below unity.

In this mode, each of the phase controllers 1006 and 1008 act as a highspeed and low impedance switch, enabling current flow from itsrespective alternator phase to its respective side of the DC motor bus1014. Switching is controlled by the microcontroller of the gensetsubsystem via the individual control lines 1016. The microcontroller canuse the phase indication from the phase detector 1004 during assistedrectification to determine the timing of all phase controller switching.

Once the microcontroller determines the timing of the phase controllerswitching, the microcontroller can provide both exact “zero crossing”based switching. This type of switch can provide the same rectificationproperties as in the Autonomous Rectification Mode. The microcontrollercan also implement “off axis” switching (e.g., in advance of zerocrossing). The microcontroller implements the “off axis” switchingduring power factor correction modes.

The microcontroller can selectively switch some of the phase controllers1006 and 1008 prior to zero crossing, in order to disconnect thealternator phases 1002 during periods of transient induction (e.g., whathappens with Wye-connected alternator architectures during the latterpart of each power cycle). By disconnecting a phase prior to inductionbeing exhibited in the phase, the net inductance of the phase isreduced. This type of switching increases the power factor of the phaseand thus reduces the induced voltage and current phase delta.

5.0 Augmentation Controller Modes

The augmentation controller 1010 can operate in at least 3 modes,including Engine Start Mode, Assisted Augmentation Mode and IsolationMode.

5.1 Engine Start Mode

In this mode, the augmentation controller 1010 connects the DC motor bus1014 directly to the battery bus 1012 enabling battery power to flowthrough the various phase controllers 1006 and 1008 to the alternator(e.g., through the alternator phases 1002) during engine start.

5.2 Assisted Augmentation

In this mode, the augmentation controller 1010 behaves like a diode witha very low (e.g., below 1 mV) forward voltage drop, allowing current toflow from the battery bus 1012 to the DC motor bus 1014 whenever thevoltage on the DC motor bus 1014 drops below the battery bus 1012voltage.

The microcontroller can select the assisted augmentation mode for theaugmentation controller 1010 when the genset subsystem is in the RippleMitigation Mode and in the Battery Augmentation Mode (e.g., includingapplicable sub modes). In these genset subsystem modes, themicrocontroller can modulate the RMS voltage output of the alternator(e.g., by controlling the ICE in the genset subsystem) as its primarycontrol mechanism for these augmentation modes. For example, themicrocontroller can modulate the RMS voltage output by controlling thethrottling of the internal combustion engine coupled to the alternator.

The microcontroller can also put the augmentation controller 1010 in theAssisted Augmentation Mode when the genset subsystem is in theGenerator-Only Mode. This enables fully autonomous battery backup in theevent of sudden loss of power output from the alternator (e.g., ICEfailure, transmission failure, etc.).

5.3 Isolation Mode

In this mode, the battery bus 1012 and the DC motor bus 1014 arecompletely isolated from each other. This mode would only be used in theevent of a battery bus fault (e.g., failure of the battery bus 1012, oneor more of the batteries, or the battery switch). The Isolation Modedisables the automatic battery backup function provided by the AssistedAugmentation mode and leaves the vehicle vulnerable to a loss-of-powerevent.

6.0 Example of Transistor-Based Phase Controllers

FIG. 11 is a first representative circuit diagram of phase controllers1100 within a motor-gen controller in a genset subsystem of a vehicle,in at least some embodiments. For example, the motor-gen controller canbe the MGC 318 in the genset subsystem 300 of FIG. 3. The motor-gencontroller can include a microcontroller 308 of FIG. 3. The illustratedpair of the phase controllers 1100 include a high-side phase controllerand a low-side phase controller.

The phase controllers 1100 is coupled to an alternator phase 1102labeled “BLDC MPhase,” a DC motor bus 1104 labeled “VMotor_Bus,” abattery bus 1106 labeled “VbatteryD.” The alternator phase 1102 is abi-directional connection to one of the phases from the alternator. Thealternator phase 1102 can be one of the alternator phases 1002 of FIG.10. The DC motor bus 1104 can be the DC motor bus 312 of FIG. 3 or theDC motor bus 1014 of FIG. 10. The battery bus 1106 can be the batterybus 314 of FIG. 3 or the battery bus 1012 of FIG. 10.

The phase controllers 1100 are further connected to control links fromthe microprocessor of the genset subsystem. For example, the phasecontrollers 1100 can receive inputs from the microcontroller including ahigh-side phase control link 1108, a low-side phase control link 1110, ahigh-side power factor correction (PFC) enable link 1112, and a low-sidePFC enable link 1114.

The phase controllers 1100 includes two pairs of current switches, suchas field effect transistors, corresponding to a high-side phasecontroller and a low-side phase controller. For example, a high-side PFCswitch 1116 and a high-side control switch 1118 correspond to thehigh-side phase controller and a low-side PFC switch 1120 and a low-sidecontrol switch 1122 correspond to the low-side phase controller.

As described above, the phase controllers 1100 can operate in anAutonomous Rectification Mode and Assisted Rectification Mode. In theAutonomous Ratification Mode, the microcontroller can keep the high-sidePFC switch 1116 and the low-side PFC switch 1120 turned on. In theAssisted rectification Mode, the microcontroller can turn on and off thehigh-side PFC switch 1116 and the high-side control switch 1118 at thesame time and turn on and off the low-side PFC switch 1120 and thelow-side control switch 1122 at the same time.

6.1 Autonomous Rectification Mode for the Transistor-based PhaseControllers

The phase controllers 1100 include a current detection circuit 1124coupled to the alternator phase 1102. The current detection circuit 1124determines either if a body diode of the high-side control switch 1118is flowing or if a body diode of the low-side control switch 1122 isflowing and indicates which body diode is flowing through voltageterminals labeled “VGateAutoHi” and “VGateAutoLo”.

A gate control circuit 1126 receives such an indication from the currentdetection circuit 1124. If the body diode of the high-side controlswitch 1118, then higher voltage is applied to a gate of the high-sidecontrol switch 1118. If the body diode of the low-side control switch1122, then higher voltage is applied to a gate of the low-side controlswitch 1122.

6.2 Assisted Rectification Mode for the Transistor-based PhaseControllers

Assisted Rectification Mode is enabled by a PFC driver circuit 1128. ThePFC driver circuit 1128 is driven by the high-side PFC enable link 1112and the low-side PFC enable link 1114. These control links allow themicrocontroller to disconnect the alternator phase 1102 during periodsof transient induction as determined by the microcontroller. Bydisconnecting the alternator phase 1102 prior to induction beingexhibited, the net inductance of the alternator phase is reduced.

6.3 Engine Start Mode for the Transistor-based Phase Controllers

As described in FIG. 10, the battery bus 1106 is connected to the phasecontrollers 1100 and supplies current to the phase controllers 1100 whenthe genset subsystem is in Engine Start Mode. In this mode, themicrocontroller manipulates the various phase control lines, such thateach pair of the phase controllers 1100 sends commuted DC power to eachof the three phases of the alternator. This enables the pairs of thephase controllers 1100 to run the alternator as a BLDC motor.

FIG. 12 is second exemplary circuit diagram of phase controllers 1200within a motor-gen controller in a genset subsystem of a vehicle, in atleast some embodiments. The phase controllers 1200 are similar to thatof the phase controllers 1100 of FIG. 11 except that the currentdetection circuit 1124 is replaced by a first current detection circuit1224 and a second current detection circuit 1225. The first currentdetection circuit 1224 can detect current flow through a body diode ofthe high-side control switch 1118 and the second current detectioncircuit 1225 can detect current flow through a body diode of thelow-side control switch 1122. The current detection circuits 1224 and1225 can be implemented respectively by rectifier chips. Each rectifierchip can couple to respective drain terminal and source terminal of thecontrol switches to determine whether the body diodes are active. Thecurrent detection circuits 1224 and 1225 can then output indication ofwhich body diode is active to the gate control circuit 1126.

FIG. 12 also illustrates a phase position output signal 1250 to themicrocontroller of the genset system. The phase position output signalis labeled as “BLDC Phase Out” in FIG. 12. The phase position outputsignal is an output to the microcontroller that indicates the phaseposition of the alternator phase 1102 when the phase controllers 1200are in the Generator Mode. In some embodiments, only one of the threepairs of the phase controllers 1200 has this output. For example, the“U” pair of phase controllers has this output. A voltage scaler can beused to bring a peak of the phase position output signal 1250 down to a5V max input voltage to be used by the microcontroller. The phaseposition output signal 1250 can also be fed into a voltage comparator soas to send the microcontroller a square pulse whenever the alternatorphase 1102 passes every 30 degrees increment of rotation. In eithercase, the phase position output signal 1250 allows the microcontrollerto sense when the microcontroller should switch the various phasecontroller control links 1108 and 1110 for each pair of the phasecontrollers 1200 during the microcontroller-directed “AssistedRectification Modes.”

7.0 Example of Diode-Based Phase Controllers

FIG. 22 is third exemplary circuit diagram of phase controllers 2200within a motor-gen controller in a genset subsystem of a vehicle, in atleast some embodiments. The phase controllers 2200 have similarfunctionalities as the phase controllers 1100 of FIG. 11 and the phasecontrollers 1200 of FIG. 12. The phase controllers 2200 include motorbus terminals 2202, ESC terminals 2204 (e.g., respectively coupled tothe ESCs 106 of FIG. 1), alternator phase terminals 2206 (e.g.,respectively coupled to different phases of a permanent magnetsynchronous motor, such as the alternator phase 1102 of FIG. 11), orbattery bus terminal 2208. The motor bus terminals 2202 are coupled to amotor bus of the vehicle (e.g., the DC motor bus 312 of FIG. 3). Themotor bus terminals 2202 can couple in parallel to a three-phaserectifier circuit 2210. The three-phase rectifier circuit 2210 caninclude three sets of diode pairs. The phase controllers 2200 includethree relays 2212. As illustrated in FIG. 22, each of the relays 2212can be respectively coupled to the ESC terminals 2204, respectivelycoupled to the alternator phase terminals 2206, and respectively coupledto nodes between the diode pairs of the three-phase rectifier circuit2210.

FIG. 13 is a first representative circuit diagram of an augmentationcontroller 1300 within a motor-gen controller in a genset subsystem of avehicle, in at least some embodiments. For example, the motor-gencontroller can be the MGC 318 in the genset subsystem 300 of FIG. 3. Themotor-gen controller can include a microcontroller, such as themicrocontroller 308 of FIG. 3. While in some embodiments theaugmentation controller 1300 can be modeled as a diode, the followingfirst exemplary circuit diagram illustrates an embodiment of theaugmentation controller that tolerates high voltage drop/wattagedissipation (e.g., 5kA-6kA to dissipate), whereas a diode would easilybreak down at the operating current of the augmentation controller 1300,The first exemplary circuit diagram further enables detection of whenthe augmentation controller 1300 is active, in order to give feedback tothe microcontroller.

The augmentation controller 1300 is coupled to a DC motor bus 1302labeled “Vmotor,” a battery bus 1304 labeled “Vbattery,” an activeindicator control link 1306 labeled “active.” The DC motor bus 1302 canbe the DC motor bus 312 of FIG. 3 or the DC motor bus 1014 of FIG. 10.The battery bus 1304 can be the battery bus 314 of FIG. 3 or the batterybus 1012 of FIG. 10. The active indicator control link 1306 maintains afirst range of voltage when the augmentation controller 1300 is active(e.g., when an electric current above a threshold, such as zero amp, isflowing from the battery bus 1304 to the DC motor bus 1302). The activeindicator control link 1306 maintains a second range of voltage when theaugmentation controller 1300 is not active.

A current switch 1308, such as a transistor and more particularly afield effect transistor (e.g., metal-oxide-semiconductor field effecttransistor (MOSEFT)), can be coupled in between the battery bus 1304 andthe DC motor bus 1302. In some embodiments, the current switch 1308 canbe a bipolar transistor, such as an insulated-gate bipolar transistor(IGBT). The current switch 1308 may include a body diode, that enablessome amount of the current to flow from the battery bus 1304 to the DCmotor bus 1302 when the current switch 1308 is off, but not vice versa.

The augmentation controller 1300 includes a current detector circuit1310. The current detector circuit 1310 here is illustrated as acomparator implemented by an op-amp. The comparator can detect when thebody diode of the current switch 1308 is active. That is, when currentis flowing from the battery bus 1304 to the DC motor bus 1302, a voltagedrop across a resistor on the battery bus 1304 can be detected by thecomparator. The comparator and thus the current detector circuit 1310can indicate activity (i.e., current flowing from the battery bus 1304)by maintaining a third voltage range at its output terminal. Thecomparator and thus the current detector circuit 1310 can indicatenon-activity (i.e., no or minimal current flowing from the battery bus1304) by maintaining a fourth voltage range at its output terminal. Forexample, the fourth voltage range is lower than the third voltage range.

The output of the current detector circuit 1310 feeds into a transistordriver circuit 1312. The transistor driver circuit 1312 applies avoltage to a gate of the current switch 1308 to turn on the currentswitch 1308 allowing more current to flow through the current switch1308 when the output of the current detector circuit 1310 indicatesactivity.

The output of the current detector circuit 1310 is also coupled to atimer circuit 1314. The timer circuit 1314 also has a second terminalcoupled to the active indicator control link 1306. The timer circuit1314 can maintain the first range of voltage at the active indicatorcontrol link 1306 when the current detector circuit 1310 indicatesactivity. The timer circuit 1314 can maintain the second range ofvoltage at the active indicator control link 1306 when the currentdetector circuit 1310 indicates non-activity. The timer circuit 1314 canmaintain the first range of voltage at the active indicator control link1306 when the current detector circuit 1310 switches between indicatingactivity and non-activity at a frequency higher than a preset threshold(e.g., around 900 Hz). For example, when the genset subsystem isoperating in the Ripple Mitigation Mode, the augmentation controller1300 and hence the current switch 1308 may be turned on and off inaccordance with a frequency of the voltage ripples from therectification process. The timer circuit 1314 presents a solid “on”state to the microcontroller even during the Ripple Mitigation Mode.

FIG. 14 is second exemplary circuit diagram of an augmentationcontroller 1400 within a motor-gen controller in a genset subsystem of avehicle, in at least some embodiments. The motor-gen controller caninclude a microcontroller, such as the microcontroller 308 of FIG. 3.The augmentation controller 1400 is similar to the augmentationcontroller 1300 of FIG. 3 except that the augmentation controller 1400includes a rectifier chip 1410 instead of the current detector circuit1310 of FIG. 13. The augmentation controller 1400 includes a DC motorbus 1402 labeled “Vmotor,” a battery bus 1404 labeled “Vbattery,” anactive indicator control link 1406 labeled “active.” The DC motor bus1402 can be the DC motor bus 312 of FIG. 3 or the DC motor bus 1014 ofFIG. 10. The battery bus 1404 can be the battery bus 314 of FIG. 3 orthe battery bus 1012 of FIG. 10. The active indicator control link 1406is similar to the active indicator control link 1306 of FIG. 13.

A current switch 1408, such as a transistor and more particularly afield effect transistor, can be coupled in between the battery bus 1404and the DC motor bus 1402. The current switch 1408 may include a bodydiode similar to the current switch 1408, that enables some amount ofthe current to flow from the battery bus 1404 to the DC motor bus 1402when the current switch 1408 is off, but not vice versa

The rectifier chip 1410 may be separately coupled to a source terminaland a drain terminal of the current switch 1408. The rectifier chip 1410can detect whether the body diode of the current switch 1408 is activeby monitoring the source and drain terminals. If the body diode isactive, the rectifier chip 1410 outputs a signal to a transistor drivercircuit 1412, similar to the transistor driver circuit 1312, to instructthe transistor driver circuit 1412 to apply a turn-on voltage to a gateof the current switch 1408 and thus lowering the resistance from thesource terminal and the drain terminal.

8.0 Flight Control

FIG. 23 is a block diagram illustrating a health monitor system 2300, inaccordance with at least some embodiments. The health monitor system2300 can be implemented in the avionics subsystem 200, such as in theflight controller 202. The flight controller can receive commands froman autopilot module (e.g., the autopilot module 204 and translate thosecommands into signals to ESCs (e.g., the ESCs 106 of FIG. 1). The flightcontroller can be operatively coupled to the autopilot module 204 and atleast one of the ESCs 106 to control the ESC based on a command from theautopilot module 204. In at least some embodiments, the flightcontroller can also implement the health monitor system 2300 to preventand/or recover from various failure scenarios of the vehicle.

Without the health monitor system 2300, the autopilot module may notrealize that a failure (e.g., in the motor or other control circuitry)has occurred until the vehicle starts to lose altitude or begins to spinout of control (e.g., as exhibited by variation in orientation). Inthese scenarios, even a 10 millisecond heads-up to the autopilot modulecan enable the autopilot module to maintain altitude and recover fromthe failure. Absent the early warning from the health monitor system2300, the autopilot module may not be able to recover from the failure.

Failure scenarios can include damage to a propeller/rotor, damage to thebearings of the motor, electrical failures (e.g., to the ESCs), or anycombination thereof. To detect these rotor scenarios, the health monitorsystem 2300 can couple to temperature probes 2302 (e.g., a temperatureprobe 2302 a and a temperature probe 2302 b, collectively referred to asthe “temperature probes 2302”), electrical probes 2306 (e.g., a currentprobe 2306 a and voltage probe 2306 b, collectively referred to as the“electrical probes 2306”), and an inertial sensor 2310.

For example, the temperature probe 2302 a can be attached at orsubstantially adjacent to the base of a motor (e.g., the drive motor 108of FIG. 1) and the temperature probe 2302 b can be attached at orsubstantially adjacent to an ESC (e.g., one of the ESCs 106). In someembodiments, the health monitor system 2300 can include only a singletemperature probe. In some embodiments, the health monitor system 2300can include more than two temperature probes. In some embodiments, thehealth monitor system can include multiple pairs of temperature probes,where each pair correspond to each pair of motor driver and ESC. Thehealth monitor system 2300 can use the readings from the temperatureprobes 2302 to detect an electrical failure to at least one of the ESCsor bearing damage to at least one of the motor drivers.

For example, the current probe 2306 a and the voltage probe 2306 b canbe attached to the circuitry of an ESC. The current probe 2306 a canmonitor the current usage of the ESC and detect short-circuits. Thevoltage probe 2306 b can detect wiring failures (e.g., open circuits).In some embodiments, the health monitor system 2300 can include multiplepairs of electrical probes 2306. For example, each pair can correspondto one of the ESCs 106 of FIG. 1. The health monitor system 2300 can usethe readings from the electrical probes 2306 to detect an electricalfailure at one or more of the ESCs.

The inertial sensor 2310 can be a sensor for detecting mechanicalvibrations. For example, the inertial sensor 2310 can be anaccelerometer or other type of motion sensor. The inertial sensor 2310can be attached to or substantially adjacent to the motor driver, therotor/propeller, the shaft of the rotor, or any combination thereof. Insome embodiments, the health monitor system 2300 can include at leastone inertial sensor 2310 in each set of rotor/propeller/motor. Thehealth monitor system 2300 can use the readings from the inertial sensor2310 to detect abnormal vibration as a precursor to an impending failureto at least one of the rotor/propeller/motor. For example, wearing of amotor bearing or damage to a rotor may result in abnormal vibration.

The health monitor system 2300 can send a warning message to theautopilot module in response to detecting an existing or impendingfailure. In response to the warning message, the autopilot module canexecute precautionary measures. For example, the autopilot module canshut down one or more of the propeller/rotor/motor/ESC sets that havebeen detected to be failing or about to fail. For another example, theautopilot module can implement a power reduction to one or more of thepropeller/rotor/motor/ESC sets that have been detected to be failing orabout to fail.

The health monitor system 2300 can provide direct and immediate feedbackto the flight controller and/or the autopilot module that a propulsionsystem (e.g., a set of propeller/rotor/motor/ESC) has failed. Forexample, the health monitor system 2300 can determine that some part ofa combination of a single rotor operate, a propeller, a motor, and anESC has failed. The health monitor system 2300 can then implement in theflight controller and/or the autopilot module's flight controlconfigurations that enable a much more graceful recovery from thefailure.

In several embodiments, the autopilot module and/or the flightcontroller can make power adjustments to the remaining propulsionsystems (e.g., non-failing propulsion systems) prior to a vehicle'sattitude degrading (e.g., departing from level flight, or otherwisecontrolled flight). This resolves the problem of the flight controllerbeing unable to recover a degraded flight plan when failure detectionrelies on altitude or other flight data. The health monitor system 2300can not only sense a propulsion failure, but also predict an impendingpropulsion failure (e.g., vibration detected by the inertial sensor2310). The health monitor system 2300 enables the flight controllerand/or the autopilot module to apply flight control laws in advance ofhazardous conditions before it even occurs. This enables the vehicle tohave much more time to plan for flight recovery. As an example, ratherthan waiting until a propulsion module fails, a flight controller and/oran autopilot module can be configured to either reduce lift power, oreven shut down on or more propulsion modules in advance of catastrophicfailure. These options can be activated, on a pre-cautionary basis, inresponse to detection of a potential or impending failure.

In these embodiments, the health monitor system 2300 enables a flightcontroller and/or an autopilot module to avoid having to make sudden(e.g., not always successful) adjustments to flight control tocompensate for failures. The vehicle protected by the health monitorsystem 2300 can prevent secondary effects of a propulsion module (e.g.,lift module) failure, which include possible onboard fire, vehicledamage due to prop/motor fragments, and/or structural damage to duevibration.

Referring again to FIGS. 1-3 and FIG. 23, portions of components and/ormodules associated therewith may each be implemented in the form ofspecial-purpose circuitry, or in the form of one or more appropriatelyprogrammed programmable processors, or a combination thereof. Forexample, the modules described can be implemented as instructions on atangible storage memory capable of being executed by a processor or acontroller. The tangible storage memory may be volatile or non-volatilememory. In some embodiments, the volatile memory may be considered“non-transitory” in the sense that it is not transitory signal. Modulesmay be operable when executed by a processor or other computing device,e.g., a single board chip, application specific integrated circuit, afield programmable field array, a network capable computing device, avirtual machine terminal device, a cloud-based computing terminaldevice, or any combination thereof. Memory space and storages describedin the figures can be implemented with the tangible storage memory aswell, including volatile or non-volatile memory.

Each of the modules and/or components may operate individually andindependently of other modules or components. Some or all of the modulesmay be executed on the same host device or on separate devices. Theseparate devices can be coupled together through one or morecommunication channels (e.g., wireless or wired channel) to coordinatetheir operations. Some or all of the components and/or modules may becombined as one component or module.

A single component or module may be divided into sub-modules orsub-components, each sub-module or sub-component performing separatemethod step or method steps of the single module or component. In someembodiments, at least some of the modules and/or components share accessto a memory space. For example, one module or component may access dataaccessed by or transformed by another module or component. The modulesor components may be considered “coupled” to one another if they share aphysical connection or a virtual connection, directly or indirectly,allowing data accessed or modified from one module or component to beaccessed in another module or component. In some embodiments, at leastsome of the modules can be upgraded or modified remotely. The systemsdescribed in the figures may include additional, fewer, or differentmodules for various applications.

One feature of particular embodiments of the disclosed technology isthat they can include a set of phase controllers for rectifying multipleAC phases from an alternator into a single DC voltage. An advantage ofthis feature is that the phase controllers enable a bi-directional AC toDC conversion. That is, the phase controllers can convert the AC phasesinto the DC voltage or commutate the alternator using a DC voltagesupplied from a battery. Another advantage of this feature is theability to provide timed disconnection of the AC phases during therectification process, allowing an external microcontroller to providepower factor correction during the rectification process. Anotherfeature is that the embodiments include an augmentation controller. Anadvantage of this feature is the ability to increase DC voltage suppliedto an aerial vehicle's motor bus by combining the rectified voltageoutput from the phase controllers and the DC voltage output of abattery. Another advantage of this feature is the ability to removevoltage ripples from the rectified voltage output from the phasecontrollers. Yet another feature is that the embodiments include an ICEto provide DC power to drive the rotors of a multi-rotor vehicle. Anadvantage of this feature is that the ICE extends the endurance of themulti-rotor vehicle by utilizing high energy density liquid fuel.

9.0 UAV Configurations

FIG. 1B, discussed above, illustrates a representative vehicle on whichpower generation systems in accordance with any of FIGS. 1A and 2-14 canbe installed. In further embodiments, such power generation systems canbe installed on air vehicles having other configurations. For example,such power generation systems can be installed on air vehicles having aquad-rotor (rather than an octorotor) configuration. In still furtherembodiments, the configurations may be implemented without necessarilyincluding power generation systems of the type described above withreference to FIGS. 1A and 2-14, and can instead include other powergeneration systems. Representative configurations can provide longendurance flight in both hover and cruise modes, as well as providingrobust vertical take-off and landing capabilities, and are describedbelow with reference to FIGS. 15-20.

FIG. 15 illustrates an air vehicle 1500 having a fuselage 1510 thatcarries wings 1520 and a tail or empennage 1540. The tail 1540 caninclude dual vertical stabilizers 1542 carried on corresponding tailbooms 1541, and a horizontal stabilizer 1543 extending between thevertical stabilizers 1542. Although not shown in FIG. 15, the wings 1520can include suitable leading edge devices, trailing edge devices, flaps,and/or ailerons, and the tail surfaces can include suitable controlsurfaces, e.g., elevator surfaces, rudders, and/or trim tabs.

The vehicle 1500 can include multiple propellers or rotors 1532,including a plurality of lift rotors 1532 a that can be used to providethe vehicle 1500 with a vertical takeoff and landing capability. Each ofthe lift rotors 1532 a (four are shown in FIG. 15) can be driven by acorresponding electric motor 1531, and can be carried by a correspondingrotor boom 1533. The motors 1531 can be powered via a power generationsystem 1530. In particular embodiments, the power generation system 1530can include a configuration generally similar to any of those describedabove with reference to FIGS. 1A and 2-14, and can accordingly includean internal combustion engine coupled to an alternator, which is in turncoupled to one or more motor/generator controllers, batteries, and/orother associated features.

The vehicle 1500 can also include one or more additional rotors, forexample, a tail-mounted pusher rotor 1532 b and/or a nose-mountedtractor rotor 1532 c. In a particular embodiment, all of the foregoingrotors are driven by electric motors, with electrical power beingsupplied by the power generation system 1530. In a relatively simpleembodiment of this arrangement, each of the rotors 1532 has a fixedgeometry, e.g., a fixed pitch.

In operation, the lift rotors 1532 a are activated for vertical takeoff.Once the vehicle 1500 has achieved a suitable altitude, the vehicle 1500transitions to horizontal flight. This can be accomplished by increasingthe thrust provided by the aft pair of lift rotors 1532 a and/ordecreasing the thrust provided by the forward pair of lift rotors 1532a. This procedure pitches the aircraft forward and downwardly and causesthe thrust of each of the lift rotors 1532 a to include a horizontalcomponent. At the same time, the pusher rotor 1532 b and tractor rotor1532 c are activated to provide an additional forward thrust component.As the vehicle 1500 gains speed in the forward direction, the wings 1520provide lift. As the lift provided by the wings 1520 increases, the liftrequired by the lift rotors 1532 a decreases. The transition to forwardflight can be completed when the lift rotors 1532 a are stopped (e.g.,with the rotors aligned with the flight direction so as to reduce drag),while the wings 1520 provide all the necessary lift, and the tractorrotor 1532 c and/or pusher rotor 1532 b provide all the necessarythrust. The foregoing steps are reversed when the air vehicle 1500transitions from forward flight to hover, and then from hover to avertical landing.

In at least some embodiments, the foregoing configuration can bedifficult to control during transitions between vertical and horizontalflight. In particular, when the vehicle transitions from verticaltakeoff to horizontal forward flight, the vehicle pitches forward toallow the lift rotors 1532 a to provide a thrust vector component in theforward direction. However, pitching the air vehicle 1500 forwardreduces the angle of attack of the wings 1520, thereby reducing theability of the wings 1520 to generate lift at just the point in theprocess when the wings 1520 are expected to increase the lift theyprovide. Conversely, during the transition from forward flight to hover(in preparation for a vertical landing), the typical procedure is to cutpower to any axial thrust rotors (e.g., the pusher rotor 1532 b and/orthe tractor rotor 1532 c) and allow the vehicle air speed to decrease tothe point that the lift rotors 1532 a may be activated. The time anddistance it takes for the air vehicle speed to decrease sufficiently maybe difficult to predict and/or adjust for (e.g., in changing windconditions) and can accordingly make it difficult for the aircraft toland accurately at a predetermined target, without engaging in multipleattempts. In other embodiments, described further below with referenceto FIGS. 16-18, the configurations can include wing geometries that aredynamically modifiable, variable, and/or configurable to address theforegoing drawbacks.

FIG. 16 illustrates an air vehicle 1600 having wings 1620, a fuselage1610, a tail 1640, and a power generation system 1630. The powergeneration system 1630 provides power to a tractor rotor 1632 c andmultiple lift rotors 1632 a.

In a particular aspect of this embodiment, the wings 1620 can beconfigured to change orientation and/or geometry in a manner thataccounts for the different pitch attitudes of the air vehicle 1600 as ittransitions between vertical and horizontal flight. In particular, eachof the wings 1620 can be coupled to the fuselage 1610 with a wing joint1621 that allows the wing 1620 to move relative to the fuselage 1610. Ina particular embodiment, the wing joint 1621 is a pivot joint and canaccordingly include an axle 1623 that allows the wing 1620 to rotaterelative to the fuselage 1610, as indicated by arrows W1 and W2. Thepivot point can be at approximately the mid-chord location of the wing1620 in some embodiments, and at other locations in other embodiments.Wing pivot motors 1622, which can receive power from the powergeneration system 1630, rotate the wings 1620 in the appropriatedirection.

In operation, as the air vehicle 1600 transitions from hover tohorizontal flight, the aircraft pitches forward (nose down) so that thelift rotors 1632 a generate a thrust component along the horizontalaxis, as described above with reference to FIG. 15. At the same time,the wings 1620 can pivot in an aft direction as indicated by arrows W1so as to provide and/or maintain a suitably high angle of attack, evenas the fuselage 1610 pitches forward. As a result, when the tractorrotor 1632 c is activated, the wings 1620 will provide lift more quicklythan if they were fixed and pitched downwardly in the manner describedabove with reference to FIG. 15.

When the air vehicle 1600 transitions from forward flight to hover, theforegoing operation can be reversed. The tractor rotor 1632 c can bestopped and, as the forward air speed decreases, the forward pair oflift rotors 1632 a can receive more power than the aft lift rotors 1632a. This will cause the vehicle to pitch nose up as well as providing areverse thrust vector, so as to more quickly slow the air vehicle 1600down. At this time, the wings 1620 can pivot forward, as indicated byarrow W2 so as to avoid stalling despite the relatively high angle ofattack of the fuselage 1610. As a result, the vehicle 1600 can be sloweddown and transitioned to hover in a quicker and more predictable mannerthan that described above with reference to FIG. 15.

In a particular embodiment, the empennage or tail 1640 of the airvehicle 1600 can be specifically configured to account for the variableangle of incidence of the wings 1620. In particular, the tail 1640 caninclude a fixed vertical stabilizer 1642 and rotatable stabilators 1643rather than fixed horizontal stabilizers with movable elevators.Accordingly, the angle of attack of the entire horizontal stabilizingsurface can be adjusted over a wide range of angles as the fuselage 1610pitches upwardly and downwardly during transitions from and tohorizontal flight. In particular, each stabilator 1643 can be coupled tothe fuselage 1610 or empennage with an axle 1644, and can be driven by acorresponding motor (not shown in FIG. 16) which is in turn powered bythe power generation system 1630. Accordingly, the stabilators 1643 canprovide sufficient elevation control authority during relatively highpitch-up and pitch-down excursions of the aircraft.

FIG. 17 is a partially schematic, plan-view illustration of an airvehicle 1700 configured in accordance with another embodiment of thepresent technology. In a particular aspect of this embodiment, the airvehicle 1700 has a configuration generally similar to that describedabove with reference to FIG. 16, but lacks a tractor rotor 1632 c.Instead, the air vehicle 1700 includes lift/thrust rotors 1632 d. Theserotors can have a configuration generally similar to those discussedabove with reference to FIGS. 15 and 16, but rather than stopping duringhorizontal flight, the lift/thrust rotors 1632 d can remain activeduring forward flight. To accomplish this result, the fuselage 1610 ispitched forward far enough to allow a component of the thrust providedby the lift/thrust rotors 1632 d to be in a forward direction. The wings1620 pivot aft as indicated by arrows W1 so as to provide lift despitethe downward pitch attitude of the fuselage 1610.

One expected advantage of the configuration shown in FIG. 17 is that itcan eliminate the need for a tractor rotor or pusher rotor, while stillproviding vertical takeoff, vertical landing, and forward flightcapabilities. Conversely, an expected advantage of the configurationdescribed above with reference to FIG. 16 is that the tractor rotor 1632c (and/or a pusher rotor) can produce a greater forward air speed, dueto the increased forward thrust provided by such rotor(s). The speedand/or endurance of this configuration may also be increased by reducingthe drag, which might otherwise result from the pitched-forward attitudeof the fuselage 1710 shown in FIG. 17.

The lift rotors described above with reference to FIGS. 15-17 haverotation axes (i.e., the axes about which the rotors rotate) that arefixed relative to the fuselage of the UAV. In other embodiments, therotation axes are moveable relative to the fuselage. For example, FIG.18 is a partially schematic, plan-view illustration of an air vehicle1800 having pivotable or otherwise moveable or configurable rotor pods1834 configured in accordance with still further embodiments of thepresent technology. The air vehicle 1800 includes a fuselage 1810 thatcarries the rotor pods 1834, in addition to wings 1820 and a tail 1840.The rotor pods 1834 can each include pairs of lift/thrust rotors 1832 d,which receive power from a power generation system 1830 configuredgenerally similar to those discussed above. In a particular embodiment,the air vehicle 1800 can include a tractor rotor 1832 c (and/or a pusherrotor, not shown in FIG. 18), and in other embodiments, the air vehicle1800 does not include either a tractor rotor 1832 c or a pusher rotor,as will be discussed further below.

The rotor pods 1834 and the wings 1820 are configured to be rotatedindependently of each other. For example, the rotor pods 1834 can bemoveably coupled to the fuselage 1810 at corresponding pod joints 1837.Each pod joint 1837 can include a pod pivot axle 1835 driven by acorresponding pod pivot motor 1836 for rotating the corresponding liftrotor pod 1834 in an aft direction (indicated by arrow P1) and a forwarddirection (indicated by arrow P2). The wings 1820 can also be pivotable.Accordingly, each wing 1820 can be coupled to the corresponding liftrotor pod 1834 with a wing joint 1821. The wing joint 1821 can include awing pivot axle 1823 driven by a wing pivot motor 1822 for rotating eachwing 1820 relative to the lift rotor pod 1834 in an aft direction (asindicated by arrow W1) and a forward direction (as indicated by arrowW2).

In operation, the lift rotor pods 1834 and the wings 1820 can be pivotedindependently of each other (e.g., in directions counter to each other)to allow a smooth transition from hover to horizontal flight and backagain. In a further aspect of this embodiment, once forward flight isachieved, the lift rotor pods 1834 can be pivoted forward as indicatedby arrows P2 by about 90° so that the lift/thrust rotors 1832 d arefacing directly forward and providing all the necessary forward thrustfor the air vehicle 1800, while the wings 1820 provide the necessarylift. In such an embodiment, the tractor rotor 1832 c can be eliminated.In still a further embodiment, the rotation of the lift rotor pods 1834can eliminate the need for the wings 1820 to rotate, as will bedescribed later with reference to FIG. 19.

With continued reference to FIG. 18, the air vehicle 1800 can include atail 1840 having pivotable stabilators 1843 and a fixed verticalstabilizer 1842. As discussed above with reference to FIG. 17, thestabilator arrangement can provide sufficient control authorities evenat high pitch angles. In other embodiments, the stabilator arrangementcan be replaced with a fixed horizontal stabilizer arrangement, forexample, when the independent rotation of the lift rotor pods 1834 andthe wings 1820 eliminates the need for high aircraft pitch angles.

In another embodiment, the configuration shown in FIG. 18 can besimplified, e.g., by eliminating the wing pivot motor 122. Furtheraspects of this embodiment can include combining the wing pivot axle1823 with the pod pivot axle 1835, so that (on each side of the fuselage1810) a single axle extends from the fuselage 1810, through the rotorpod 1834 to the wing 1820. In yet a further aspect of this embodiment,the rotor pod 1834 then pivots freely on the axle. With this baselineconfiguration, the pivot motor 1836 (which was previously described asdriving the rotor pod 1834) instead drives the wing 1820, as indicatedby arrows W1 and W2. The rotational position of the rotor pod 1834 aboutthe axle is determined by the normal dynamic lifting forces provided bythe forward and aft rotors 1832 d. For example, if the aft rotor 1832 dprovides a greater lifting force than the forward rotor 1832 d, then therotor pod 1834 will rotate (pitch) forward. For conventional lift, hoverand landing maneuvers, the two lift rotors 1832 d on each rotor pod 1834can provide a combined lift force that maintains the air vehicle 1800 ina roughly horizontal orientation.

In yet a further simplification of the arrangement described immediatelyabove, the pod pivot motor 1836 can be replaced with a releasable brake.When locked, the brake can prevent the rotor pod 1834 from rotatingrelative to the fuselage 1810. When the brake is unlocked, the rotor pod1834 can rotate freely relative to the fuselage 1810. In either mode,the wing 1820 can remain in a fixed position relative to the fuselage1810. During take-off, the brake prevents the fuselage 1810 (which maybe nose-heavy) from pitching forward. Once the air vehicle 1810 attainsa sufficient forward speed, and/or the tractor rotor 1832 c providessufficient airflow over the stabilators 1843, the stabilators 1843 canprovide sufficient pitch control authority to allow the brake to bereleased. In one embodiment, the brake can be carried by the fuselage1810, and in another embodiment, the brake can be carried by the rotorpod 1834.

In still another embodiment, the rotor pods 1834 can be positionedfurther away from the fuselage 1810, along the length of the wings 1820.Accordingly, the rotor pods 1834 are not connected directly to thefuselage 1810, but are instead connected between an inboard portion ofthe wing 1820 and an outboard portion of the wing 1820. In thisconfiguration, the pods 1834 can be fixed or pivotable in accordancewith any of the embodiments described above with reference to FIG. 18.

FIG. 19 illustrates an air vehicle 1900 configured in accordance withstill a further embodiment of the present technology. In one aspect ofthis embodiment, the vehicle 1900 include wings 1920 that are fixed to acorresponding fuselage 1910. Lift rotors 1932 a are carried by rotorpods 1934 located at the outboard ends of the wings 1920. The rotor pods1934 can be rotated relative to the wing 1920 (as indicated by arrows P1and P2) via corresponding pod pivot motors 1936 and pod pivot axles1935. The lift rotors 1932 a are powered by a power generation system1930, which can also power an optional pusher rotor 1932 b or tractorrotor (not shown in FIG. 19). The tail 1940 can include twin booms 1941,each carrying a vertical stabilizer 1942, with a horizontal stabilizer1943 carried by the vertical stabilizers 1942. In other embodiments, thetail 1940 can have other configurations. In some configurations, the airvehicle 1900 can include a pusher rotor 1932 b, and in otherconfigurations, the pusher rotor 1932 b can be eliminated.

One potential advantage of the configuration shown in FIG. 18 comparedto that shown in FIG. 19 is that the rotor pods are closer to thefuselage, therefore reducing the bending load on the wing. Conversely,one potential advantage of the arrangement shown in FIG. 19 relative tothat shown in FIG. 18 is that the number of pivot joints is reduced.

FIG. 20 is a partially schematic, side-view illustration of an airvehicle 2000 having a movable, changeable and/or otherwise configurablelift rotor boom in accordance with another embodiment of the presenttechnology. In one aspect of this embodiment, the air vehicle 2000includes two lift rotor booms 2034 (one of which is visible in FIG. 20),each of which carries a pair of lift rotors 2032 a. Each boom 2034 canbe coupled to the fuselage 2010 with a boom joint 2037. In a particularembodiment, the boom joint 2037 can include a boom pivot axle 2035 thatallows the lift rotor boom 2034 to pivot clockwise and counter-clockwiserelative to the fuselage 2010. The air vehicle 2000 can also include afixed wing 2020. In a particular aspect of this embodiment, the wing2020 has a high-wing configuration so as to increase the spacing betweenthe wing 2020 and the boom joint 2037. This arrangement allows the liftrotor boom 2034 to pivot through a suitable angle without interferingwith the wing.

In operation, the lift rotor boom 2034 can be positioned (e.g., locked)in the generally horizontal orientation shown in FIG. 20 during avertical takeoff (and landing) maneuver. To transition to horizontalflight, the lift rotor boom 2034 pivots counter-clockwise such that thelift rotors 2032 a are positioned to provide a forward thrust componentto the air vehicle 2000. Because the air vehicle 2000 need not pitchdownwardly to place the lift rotors 2032 a in this orientation, the wing2020 can remain fixed relative to the fuselage 2010. In a particularaspect of this embodiment, the air vehicle 2000 can include a tail orempennage 2040 having a vertical stabilizer 2042 and a horizontalstabilator 2043. The stabilator 2043 (as opposed to an elevator) canprovide sufficient control authority to handle pitching moments that maybe caused by the moving lift rotor boom 2034.

One feature of the configuration shown in FIG. 20 is that the pivotinglift rotor boom 2034 can eliminate the need for a movable wing. As aresult, the wing 2020 can provide suitable lift without changing itsincidence angle. In addition, the pivot angle through which the liftrotor boom 2034 travels is sufficient to direct forward thrust from thelift rotors 2032 a without the need for a pusher or tractor rotor.

FIG. 21 is a partially schematic, top isometric illustration of an airvehicle 2100 having lift rotors that can be pitched between a generallyforward-facing position and a generally upward-facing position, inaccordance with yet another embodiment of the present technology. In oneaspect of this embodiment, the air vehicle 2100 includes a fuselage2110, wings 2120 extending outwardly from the fuselage 2110, and a tailor empennage 2140 positioned aft of the wings 2120. The empennage 2140can include a vehicle horizontal stabilizer 2143 and a vehicle verticalstabilizer 2142. The horizontal stabilizer 2143 can include a vehiclerudder 2145 for controlling vehicle yaw, and the horizontal stabilizer2143 can include vehicle elevators 2144. The vehicle elevators 2144 canbe activated to control the overall pitch attitude of the air vehicle2100.

The air vehicle 2100 can further include multiple pitch rotors 2132 thatcan be used to lift the air vehicle 2100 and/or provide forward thrustfor the air vehicle 2100, depending on factors that include theorientation of the rotors 2132. Accordingly, the rotational axes of therotors 2132 can be reoriented relative to the air vehicle's direction offlight. In a particular embodiment, the rotors 2132 can be carried bycorresponding rotor pods 2134. The rotor pods 2134 can be carried towardthe ends of the wings 2120, in an embodiment shown in FIG. 21, and canbe carried at other locations of the vehicle in other embodiments. Inany of these embodiments, the rotor pods 2134 can be rotatable relativeto the wings 2120 and/or the fuselage 2110 and can be coupled to thewings 2120 at corresponding pod joints 2137. Accordingly, each rotor pod2134 can be rotated toward a forward-facing position (as indicated byarrow F) and can be rotated in the opposite direction toward anupward-facing orientation, as indicated by arrow U.

The rotors 2132 can include forward rotors 2132 a positioned forward ofaft rotors 2132 b when the corresponding rotor pod 2134 is in agenerally horizontal, upward-facing position. In at least somemulti-rotor aircraft, the rotor pods 2134 are rotated by increasing theforce differential between the force provided by the aft rotor 2132 band the force provided by the forward rotor 2132 a. For example, if theaft rotor 2132 b is powered to provide more force than the forward rotorat 2132 a, then it lifts the aft portion of the rotor pod 2134, causingthe rotor pod 2134 to rotate in the forward direction, as indicated byarrow F. To rotate the rotor pod 2134 in the opposite direction(indicated by arrow U), the force deferential is reversed, with theforward rotor 2132 a providing more force than the aft rotor 2132 b.

In at least some embodiments, when the air vehicle 2100 has asignificant portion of its lift provided by airflow over the wings 2120,the available force differential between the aft rotor 2132 b and theforward rotor 2132 a can be relatively small. Accordingly, it can bedifficult to rotate the rotor pod 2134 when the air vehicle 2100 has asignificant forward velocity. To address this potential issue,embodiments of the air vehicle 2100 can include one or more podelevators 2134 that can be actuated to change the pitch angle of therotor pod 2134 and therefore the orientation of the rotors 2132, even atrelatively high forward air speeds. In particular, the pod elevators2134 can rely on the relatively high forward air speed to provide theaerodynamic forces used to pitch the rotor pod 2134 in the directionsindicated by arrows F and V. For example, in a representativeembodiment, the rotor pods 2134 can each include a pod horizontalstabilizer 2133 that carries the pod elevator(s) 2134. To pitch therotor pod 2134 and rotors 2132 forward, as indicated by arrow F the podelevators 2134 are rotated downwardly relative to the pod horizontalstabilizer 2133, as indicated by arrow A. To rotate the rotor pod 2134in the opposite direction, as indicated by arrow U, the pod elevators2134 are rotated upwardly, as indicated by arrow B.

In one aspect of the foregoing embodiments described above withreference to FIG. 21, the system can include features to prevent orinhibit Dutch roll. In one embodiment, the system can include a torquetube that extends through the wings 2120 to connect the pods 2134 andsynchronize the motion of the pods. In another embodiment, the pods 2134can be locked, for example, during low speed operation (which is whereDutch roll typically occurs) to prevent or reduce Dutch roll. The pods2134 can then be unlocked at higher speeds where Dutch roll is lesslikely. In still another embodiment, the elevator control can bereplaced with actuators that drive the pods 2134, generally in themanner described above with reference to FIG. 19.

One advantage of at least some of the features described above withreference to FIG. 21 is that the pod elevator 2134 can improve theability for the rotors 2132 to rotate at relatively high vehicle airspeeds. In particular, at such air speeds, it may be difficult for therotors to change orientation based solely on the differential forceavailable between the forward and aft rotors 2132 a, 2132 b.

One feature of several of the embodiments described above with referenceto FIGS. 15-20 is that they can include power generation systems thatprovide electric power to one or more rotors via an internal combustionengine coupled to an alternator, battery, and associated switchingfeatures. Accordingly, the foregoing power generation arrangements,features, and techniques need not be limited to octo-copters, but caninstead be applied to a variety of unmanned air vehicle configurations.

Another feature of at least some of the foregoing configurations is thatthey can include one or more lift rotors in combination with one or moretractor/pusher rotors, all of which can be electrically driven, withelectrical power provided by a combustion engine in combination with analternator, battery and associated switching features. An associatedfeature is that electrical power can be available to any propeller orrotor at any time, independent of the flight mode of the aircraft (e.g.,independent of whether the aircraft is taking off, cruising, hovering,landing or engaging in another maneuver). An advantage associated withthis level of flexibility is that it can improve the smoothness, speed,and/or efficiency of transitions between one mode and another. Anotheradvantage is that it allows the operator (human and/or automated controlsystem) to select from multiple possible combinations of lift forces.Accordingly, the operator can select the combination that provides thedesired performance characteristic for a given mission and/or portion ofa mission. The performance characteristic can include endurance, speed,number of take-off and landing cycles, and/or other measures. For any ofthese characteristics, the ability to control what fraction of lift isprovided by the wings and what fraction is provided by the lift rotorscan improve the performance characteristic. For example, theconfigurations described above can support long endurance forward flightat speeds less than would be permissible by a fixed wing aircraft, dueto the lift available from the lift rotors. The endurance can also begreater than that available with a basic quadrotor vehicle, due to thelift provided by the wings.

Another feature of at least some of the foregoing embodiments is thatthe wings can have a variable geometry and/or configuration. Anadvantage of this feature is that it can improve the transitions betweenhorizontal and vertical flight, for example, by reducing the amount oftime required to make the transition, by making the transition smoother,and/or by making the transition more predictable and repeatable, thusimproving the accuracy with which the aircraft can be directed.Particular embodiments were described above in the context of pivotingwings, e.g., wings for which the entire chord pivots so as to change theangle of attack of the wing as opposed to conventional pivoting leadingand/or trailing edges. In other embodiments the wings can have otherarrangements including wing warping arrangements, and/or an arrangementof leading and/or trailing edge devices that allow the angle of attackand center of lift of the wing to be changed dynamically. The foregoingembodiments differ from conventional arrangements of deployable leadingand trailing edges devices. Such conventional devices can shift thecenter of lift of an airfoil, but do not directly change the angle ofattack of the airfoil—instead, the angle of attack of the airfoil maychange as an end result of the aerodynamic forces acting on the leadingand/or trailing edge devices, if those forces are not counteracted.Still further embodiments include any suitable combination of theforegoing features (e.g., variable geometry wings, variable incidence orangle of attack wings, and/or leading or trailing edge devices that varythe center of lift). Configurations in accordance with any of theforegoing embodiments can include the same or a suitable differentnumber of vertical lift rotors, tractor rotors and/or pusher rotors.

The foregoing features alone and/or in combination with other featuresdescribed herein, can provide several advantages when compared withexisting quadrotor or quadcopter configurations. For example,conventional quadrotor UAVs that rely exclusively on electric powerproduced by on-board batteries typically have a relatively short range,at least in part because the lift rotors use a significant amount ofpower and do not take advantage of lift created by the flow of air overa fixed lifting surface (e.g., a wing). Typical fixed rotor vehicles canhave a significantly limited forward flight speed and range, and, due tothe power required to maintain a hover configuration, can suffer frompoor hover endurance. Still further, the constraints on endurancetypically limit such configurations to one takeoff and one landing cycleper battery charge.

Conventional hybrid quadrotors, which have a wing in addition to liftrotors, typically use electric motors for lateral motion and lift, orelectric motors for lift and gas-driven motors for lateral motion. Bothconfigurations can provide more endurance than an all-electricmulti-rotor vehicle. For example, conventional hybrid quadrotors cantake off and land more than once. However, such conventional hybridquadrotors are still limited in the number of takeoff and landing cyclesthey can complete with the limited on-board energy supply. In addition,such vehicles can have limited endurance because the lift rotors do notcontribute significantly to forward thrust during forward flight, andinstead are typically stopped during forward flight.

Aircraft in accordance with several of the configurations disclosedherein can overcome some or all of the conventional vehicle drawbacksdescribed above. In particular, such aircraft can achieve long endurancein a forward flight mode and long endurance in a hover mode. Suchaircraft can take off and land multiple times and may therefore besuitable for missions (e.g., package delivery) that require and/orbenefit from this capability. Furthermore, such vehicles can operate atslow forward speeds, e.g., below the normal wing stall speed, by usingaugmented lift available from the lift rotors, and/or adjusting theangle of attack of the wing such that the wing is unstalled or remainsat an angle of attack below the critical angle of attack, even at a lowforward speed.

Still further embodiments can provide additional advantages. Forexample, many of the configurations described herein are designed totake off and land vertically and accordingly may not includeconventional landing gear. Instead, such vehicles can include skids.However, in particular embodiments, the vehicles can be configured toinclude wheeled landing gear or other landing gear that allow for atakeoff and/or landing roll. Normally, such vehicles would include flapsto increase lift at low speeds. Vehicles in accordance with embodimentsof the present technology need not include flaps, and can instead relyon lift rotors to provide lift at a low forward speed during approachand landing. One instance in which such a capability may be advantageousis if one of the lift rotors (e.g., one of four lift rotors) fails priorto landing. In such a condition, the vehicle cannot be readilycontrolled in hover and in particular, the non-operational rotor reducesthe available yaw authority to the point where a controlled verticallanding is difficult or impossible. However, with configurations inaccordance with those described above, the remaining active lift rotorscan be re-oriented (e.g., pivoted) to provide air flow over a tailsurface of the vehicle to provide stability and control about the yawaxis. In addition to or in lieu of the foregoing, the variable incidencewing can allow the vehicle to land at low forward air speeds without theneed for flaps. In a particular aspect of the foregoing embodiments, anadditional one of the lift rotors may be deliberately stopped (e.g., sothat only two lift rotors are active in a four-rotor configuration, withone rotor inactive due to a malfunction, and the other deliberately shutdown) to provide for a symmetric configuration.

From the foregoing, it will be appreciated that specific embodiments ofthe disclosed technology have been described herein for purposes ofillustration, but that various modifications may be made withoutdeviating from the technology. For example, the number of alternator ACphases may be only two phases or may be more than four phases. Certainaspects of the invention described in the context of particularembodiments may be combined or eliminated in other embodiments. Forexample, the microcontroller, the augmentation controller, and the phasecontrollers can be combined into an integrated circuit. An individualmotor and/or actuator can power multiple devices, e.g., multiplerotatable wings. Particular embodiments were described above in thecontext of vehicles with four lift rotors. In other embodiments, thevehicles can include more rotors, e.g., eight rotors arranged in tworows of four, or four pairs of co-axial, counter-rotating lift rotors.Aspects of the foregoing embodiments have been described generally inthe context of UAVs. In other embodiments, air vehicles havingconfigurations and/or battery augmented power systems generally similarto those described above can be used for manned flight. Further, whileadvantages associated with certain embodiments of the disclosedtechnology have been described in the context of those embodiments,other embodiments may also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages to fall within thescope of the technology. Accordingly, the disclosure and associatedtechnology can encompass other embodiments not expressly shown ordescribed herein.

I claim:
 1. A multi-rotor vehicle system comprising: a direct current(DC) powered motor coupleable to a rotor; an electronic speed controllercoupled to the DC-powered motor to control the speed of the DC-poweredmotor by regulating electric current supplied to the DC-powered motor;and a genset subsystem coupled to the electronic speed controller topower the electronic speed controllers through a DC motor bus, whereinthe genset subsystem includes: a battery set including one or morebatteries; an alternator having a mechanical movement input and amultiphase alternating current (AC) output; and a motor-gen controllerhaving a phase control circuit configured to rectify the multiphase ACoutput of the alternator to produce a rectified DC feed to theDC-powered motor; and wherein the motor-gen controller is activatable todraw DC power from the battery set to produce the rectified DC feed. 2.The multi-rotor vehicle system of claim 1, wherein the motor-gencontroller is configured to commutate the alternator by drawing DC powerfrom at least one battery in the battery set.
 3. The multi-rotor vehiclesystem of claim 1, wherein the motor-gen controller is configurable todraw the DC power from only a subset of the batteries in the batteryset.
 4. The multi-rotor vehicle system of claim 1, wherein thealternator is a brushless DC (BLDC) alternator.
 5. The multi-rotorvehicle system of claim 1, wherein the genset subsystem furthercomprises: an augmentation controller configured to fill in voltageripples in the rectified DC feed from the phase control circuit usingthe DC power from the battery set.
 6. The multi-rotor vehicle system ofclaim 5, wherein the augmentation controller is configurable to providethat the alternator produces less voltage than a nominal voltage of abattery in the battery set.
 7. The multi-rotor vehicle system of claim1, wherein the phase control circuit further comprises phase controllersimplemented by transistors to thereby enable lossless rectification. 8.The multi-rotor vehicle system of claim 1, wherein the phase controlcircuit further comprises diodes.
 9. The multi-rotor vehicle system ofclaim 1, further comprising: a fuel-based power source that generatesmechanical movement and is coupled to the mechanical movement input ofthe alternator.
 10. The multi-rotor vehicle system of claim 9, whereinthe fuel-based power source is an internal combustion engine.
 11. Amulti-rotor vehicle system comprising: a direct current (DC) poweredmotor coupleable to a rotor; an electronic speed controller coupled tothe DC-powered motor to control the speed of the DC-powered motor byregulating electric current supplied to the DC-powered motor; a gensetsubsystem coupled to the electronic speed controller to power theelectronic speed controllers through a DC motor bus, wherein the gensetsubsystem includes: a battery set including one or more batteries: analternator having a mechanical movement input and a multiphasealternating current (AC) output; and a motor-pen controller having aphase control circuit configurable to rectify the multiphase AC outputof the alternator to produce a rectified DC feed to the DC-poweredmotor; and wherein the motor-gen controller is configurable to draw DCpower from the battery set to produce the rectified DC feed; and anautopilot module to execute a flight plan for the multi-rotor vehiclesystem; and a flight controller operatively coupled to the autopilotmodule and the electronic speed controller to control the electronicspeed controller based on a command from the autopilot module.
 12. Themulti-rotor vehicle system of claim 11, further comprising: a sensorcoupled to the electronic speed controller or the DC-powered motor; andwherein the flight controller implements a health monitor system thatdetects a failure or impending failure based on at least a reading ofthe sensor.
 13. The multi-rotor vehicle system of claim 12, wherein thesensor is at least one of a current sensor, a voltage sensor, or atemperature sensor coupled to the electronic speed controller.
 14. Themulti-rotor vehicle system of claim 12, wherein the sensor is at leastone of a temperature sensor or an inertial sensor coupled to theDC-powered motor.